Rather than a kinetic approach, say officials and experts, the United States has adopted a method that relies on spy satellites’ most vulnerable aspect: the need for constant housekeeping from the ground.

To maintain satellite orbits, particularly low Earth orbits, controllers on the ground must send their satellites a constant barrage of signals from ground stations around the world. For example, the United States maintains the Satellite Control Network, a string of eight tracking stations in places as remote as Thule Air Base on Greenland, and Diego Garcia in the Indian Ocean.

By interfering with those signals — called telemetry, tracking and control signals — the United States can put satellites out of commission for critical periods of time or send them spiraling out of control. Intelligence experts call the strategy “electronic negation” or “intrusion.”

"The best ASAT [anti-satellite device] is not a weapon that detonates next to an enemy satellite," said William E. Burrows, a journalism professor at New York University who is also the author of "Deep Black," a book on spy satellites. "Instead, it would be a signal that would tell the satellite to take the rest of the afternoon off."

Such a device is best for a number of reasons, experts say. Sending up a flurry of ASATS —missiles or space mines — would be obvious and could start an arms race in space or trigger a war in a crisis. Blinding an adversary has had that effect for eons. Using signals intelligence and intrusion is far subtler, and thus more difficult for the victim to detect.

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Windrem, Robert. "U.S. favors stealthy anti-satellite strategy." MSNBC News. April 11, 2007.